Newer airplanes are equipped with wireless communication capability (e.g., WiFi) to facilitate the exchange of large volumes of data between airplanes and airline operation centers during aircraft gate turnaround time. However, wireless connectivity has encountered issues at many airports: limited WiFi infrastructure and bandwidth and interference from passengers' WiFi enabled devices. Additionally, there is a data security risk associated with sharing the common wireless channels.
An alternative to wireless communications is to use wired data communications over airport ground power lines that already exist. However, data transmission over power lines faces two fundamental challenges. First, data transmissions over power lines suffer from large transients, noise and crosstalk on the power lines. Each time an electric load turns on/off, or changes its power consumption levels, it introduces glitches and asymmetries into the power line. Switching power supplies and power inverters create undesirable harmonics. Generators, compressors, motors, relays, fault-circuit interrupters, transistors and rectifiers create noise with their respective signatures. As an example, a commercial airplane parks at an airport terminal gate and receives electrical power from a Ground Power Unit (GPU) hung beneath a jet-way (passenger loading bridge). This GPU provides an average current of 730 amps (A). Due to load variation (adding and shedding), this current may go up to maximum of 1,100 A, drop to 500 A in 10 milliseconds (MS), then decay to a steady state of 260 A in 130 ms. Such disturbances increase the likelihood of signal degradation as seen by a Broadband Power Line (BPL) receiver, and signal attenuation as seen by a BPL transmitter. Performance of BPL communication can also be degraded due mismatch of line impedance and signal reflections by the connectors.
To overcome large transients and noise on power lines, signal strength from a BPL device during its transmitting mode is increased to compensate for degraded signal-to-noise ratio. Increasing the transmission power increases the signal-to-noise ratio and thus reduces error rate. Generally, it is desirable to transmit data end-to-end with an error rate less than 0.001%. Increasing the transmission power sufficient to obtain an acceptable signal-to-noise ratio (i.e., to obtain a desired low error rate), however, produces frequency harmonics, unwanted radiated energy and increased electromagnetic interference with other systems operated at the same frequency range.
A second challenge for communications over ground power lines is radio interference. BPL modems based on the HomePlug audio-video 2 (AV2) standard operate in the 1.8 MHz to 86 MHz band, while BPL modems based on the g.hn standard by the International Telecommunication Union's Telecommunication Standardization sector (ITU-T) operate in the 2 MHz to 100 MHz band. Devices configured according to these two standards operate in the high frequency (HF) and very high frequency (VHF) range occupied by military, aeronautical, amateur radios, and broadcasters. Unlike coaxial line or twisted-pair lines, power lines are unshielded with no inherent noise rejection, thus acting as outdoor antennas for the 2 MHz to 100 MHz signals they carry. Widespread deployment of BPL may have a detrimental effect upon military HF radio communications.
Moreover, interference from nearby systems in close proximity, such as an airport terminal gate area with multiple BPL outdoors installations, further causes signal degradation as the BPL modems may not be able to determine a specific frequency among other signals in the same bandwidth.
When errors in communication become significant, BPL devices become less efficient (packet lost and data retransmission), inoperative or operate in an undesirable manner (data corrupted or contaminated but undetected).